Energetic materials store significant chemical energy that can be released to provide energy for a wide range of purposes. Typical uses of energetic materials include as propellants, explosives, and fuels. Nanoenergetic composites take advantage of the high surface area ratios of nanoparticles to enhance the mass transfer process and rate of energy release in the self-sustaining fuel-oxidizer energetic materials reaction. Reducing the fuel and oxidizer grains physically to the nanoparticle regime minimizes mass transfer effects.
Sol-gel processes are wet-chemical process used for the fabrication of metal oxides and other materials from a chemical solution that reacts with another precursor to produce a colloid of nanometer or micrometer scaled particles dispersed in a solvent (sol), which proceeds to form an inorganic network containing a liquid phase (gel). The precursor solvent can be deposited or cast into a desired film or into a container that defines a shape prior to the formation of the gel phase. Metal oxides are formed by connecting metal particles with oxygen (M-O-M) or hydroxide (M-OH-M) bridges. Drying removes the liquid phase from the gel, which can be post-processed to enhance mechanical properties of the material.
A sol-gel approach for nanoenergetic composites has been described is by researchers at Lawrence Livermore National Laboratories. See, Clappsdale et al, “Synthesis and Characterization of Mixed Metal Oxide Nanocomposite Energetic Materials,” UCRL-PROC-204118, International Pyrotechnics Seminar Fort Collins, Colo., Jul. 12, 2004 through Jul. 16, 2004. The materials described include metal oxide/silicon oxide nanocomposites in which the metal oxide is the major component. A fuel metal, such as aluminum, is incorporated into the metal oxide/silicon oxide matrix to form energetic materials that are based on thermite reactions. Example metal oxides are tungsten trioxide and iron(III) oxide. The paper describes a sol±gel approach in order to manufacture the thermite composites. Though the use of porous iron oxide prepared using sol-gel technique in nanoenergetic application is well-known and its preparation has been expounded earlier by other researchers either by using sol-gel technique, the prior techniques result only in the formation of disordered porous structure.
Typical known methods of preparing copper oxide nanoparticles prepare the nanoparticles directly from copper ethoxide. This is an expensive material that is not readily available in commercial quantities.